Hugh mcdonald



(NoModel.)

' H. MGDONALD. Furnace Shield. No.. 236,235. Patented Jan. 4,1881.

ILPETERS, PNOTQUTHOGRA'HER. wAsHxNGToN. :J c.

l lUNrrn HUGH MGDONALD, OF ALLEGHENY, PENNSYLVANIA.

FU RN'ACE-SHIELD.

SPECIFICATION forming part of Letterslatent No. 236,235, dated January4, 1881.

Application filed April 2, 1880.

To all whom t may concern Beit known that I, HUGH MCDONALD, ofAllegheny, county of Allegheny, State of Pennsylvania, have invented ordiscovered a new and useful Improvement in Furnace- Shields 5 and I dohereby declare the following to be a full, clear, concise, and exactdescription thereof, reference being had to the accompanying drawings,making a part of this specification, in which--like letters indicatinglike parts- Figure l is a side elevation, slightly in perspective, of apuddling or boiling furnace with my improved shield applied thereto; andFig. 2 is a sectional view through the shield and the door ofthepuddling-furnace, showing the position of the shield when in userelative to the furnace.

The excessive heat required in the puddlin g or boiling or reheating orother treatment of iron or steel is such as to be exceedingly oppressiveto the workmen, and to interfere materially with the best exercise ofskill in doing the work. As a device for guarding against the edects ofsuch high temperature, and toenable the workman to bring out a maximumamount of work in the best condition with the least exposure to himself,shields have been arranged in front of the furnace-door.

My present invention relates to the construction of a shield for suchuse, and while I have shown it as applied to apuddling orboiling furnaceI do not limit myself to the combination of it with any partieularkindor class of furnace, butinclude herein the construction described in itsapplication to any kind or class of furnace where protection to theworkman is desired as against excessive heat.

A puddling-furnace of ordinary construction is shown at B. Thevertically-movable door D, through which to charge the furnace andremove the product, is of the usual or any known construction. It isprovided with the usual stopper or work-ing hole d. Since the workmanhas to stand opposite-the door in charging, workin g the charge, makingup, and removing the ball, protection is chiefly needed at this point.To this end I suspend a movable shield, A, opposite the door, but at alittle distance therefrom, as shown in Fig. 2, chiefly in order that theair may circulate (No model.)

freely in the intermediate space, and lessen to that extent theconduetionof heat from the furnace to the shield. This shield iscomposed of a plate of metal, a, extendingover the whole or the greaterpart ofthe back of the shield, Q

` properties of such materials as non-conductors are so well known inother branches of the art that the skilled workman will have nodifficulty in proportioning the thickness according to the amount ordegree of protection desired. For ordinary purposes I consider athickness of about three or four inches sufficient.

This shield is, by preference, made large enough to cover so much of theside of the furnace as comes within the range of the usual positions ofthe Workman in doing his work, and is made with a recess in its loweredge of suitable size and position for uncovering the stopperhole, asshown, and the ange a2 around this recess gives room for the propermanipulation of the workmans tools. It may be made movable in anysuitable way, as by being hinged at one edge, or raised andlowered by alever, or, as the preferable Way, it may be hung by straps c andfriction-rollers c on a track-rail, b, which is supported from thefurnace-frame by brackets b', so as to be run to one side and out of theway to a position indicated by dotted lines whenever necessary forcharging or xin g the furnace, or for removing the ball, the workman forthis purpose manipulating the shield by the handles at a4.

The structure of shield described may be modied somewhat without anysubstantial departure from the scope of the present invention, as, forexample, an outside plate may be added, as shown by dotted lines at c,Fig. 2, so as to give a hollow box, in which case the non-conductingmaterial may be run in a plastic state or filled in dry, as may bepreferred; or, as another modification, a like layer of non- IOOconducting plastic material may be placed ou the back of the plate a,asillustrated by dotted lines e of Fig. 2; but in this case the shieldshould be hung a little farther from the furnace than is represented, inorder that the proper air-space may be provided between the two, andhere, as before, any suitable plastic having a low heat-conducting powermay be employed.

The principal object I have in View in the making of a shield in themanner herein described is to utilize for the purpose such materials ascan be best employed in a pulverized, broken, or oomminuted state; andWhile the best results may be secured by the use ot' material having.,rthe lowest heat-conducting power, other thin gs being equal,it isstilltrue thaty advantageous results may follow from the use ofmaterials which are much better conductors of heat than those which Ihave specifically named. Hence, by the term like material, as hereinused, I mean a material pulverized, ground, broken, or comminuted; andas to its heat-conducting power, itis only essential that it be solow asto be adapted to operate asa barrier or shield under the circumstancesnamed.

I claim herein as my invention* A furnace-shield consisting ofY ametalplate lined on one or both sides with plaster-of-paris, lime, or otherlike material having a low power as a conductor of heat, movablyarranged at the side of a furnace opposite the door, anda littl 3distance therefrom, substantially as and for the purposes set forth.

In testimony whereof I have hereunto set my hand.

HUGH MCDONALD.

Witnesses:

R. H. WHITTLESEY, G. L. PARKER.

